Ball joint

ABSTRACT

A ball and socket joint is provided having a casing with a bore closed at one end with a cover, a ball in the casing and a resilient bearing between the ball and the wall of the bore, the bore being cylindrical from the opening closed by the cover to a point below the maximum cross-section of the ball where it merges into a frustoconical portion terminating adjacent the ball pin in an annular inwardly extending flange, the external configuration of the bearing corresponding to that of the wall of the bore, having protuberances adjacent to and compressed by the cover and having circumferentially spaced longitudinal slots in that portion thereof which is frusto-conically shaped to reduce the volume of the bearing and reduce friction when the ball moves with respect to the bearing.

1 11 1 1111 3,77,327 Outlet Jan. 22, 1974 [54] BALL JmNT FOREIGN PATENTSOR APPLICATIONS Inventor: Richard Cutler, wlesenweg, 777,002 6/1957Great Britain 187/90 c Germany [73] Assignee: Gottfried Renter Gmbl-ll,Lemforde, 'T Examinep'pfndrew 'a Germany Attorney, Agent, or FIrmClelleW. Upchurch PP 201,081 A ball and socket joint is provided having acasing with a bore closed at one end with a cover, a ball in 30 F A H PD ta the casing and a resilient bearing between the ball and 2 0 pp caon "on y 20 57 5B 7 the wall of the bore, the bore being cylindricalfrom 197 the opening closed by the cover to a point'below the 1 maximumcross-section of the ball where it merges ig i ;3% into a frustoconicalportion terminating adjacent the [58 d g 90 C ball pin in an annularinwardly extending flange, the 1 o are external configuration of thebearing corresponding to 56] R f n Cit d that of the wall of the bore,having protuberances ade ere ces e jacent to and compressed by the coverand having cir- UNITED STATES PATENTS cumferentially spaced longitudinalslots in that portion 3,210,105 10/1965 Vogt 287/87 thereof which isfrusto-conically shaped to reduce the 3,554,586 1 Cutler 287/87 volumeof the bearing andreduce friction when the 3,375,028 3/1968 Patton287/90 R ban moves with respect to the bearing 3,220,755 [1/1965Gottschald et al 287/87 3,530,495 9/1970 1 Finde1..; 287/87 4 Claims, 2Drawing Flgures PATENTED JAN 2 2 I974 sum 2 or 2 iiiiiii!'HJHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:

1 BALL JOINT This invention relates generally to ball joints and moreparticularly to an improved resilient bearing for such joints.

A ball joint having an improved resilient bearing is described in myU.S. Pat. No. 3,554,586. The ball and hearing are enclosed in a suitablecasing having a bore. The bore has a substantially cylindrical portionadjacent the end through which the ball and ball pin are inserted. Thecylindrical portion of the bore merges with a frusto-conical ortrunconical portion adjacent the lower portion of the ball and justabove an inwardly extending flange about the open end adjacent the ballpin or stem A resilient'be'aring having an external peripheralconfiguration corresponding to that of the bore and a spherical cavityadapted to fit about the ball is provided with one or more upwardlyprojecting protuberances on'its surface adjacent the cover which closesthat end of the casing above the ball. The edge of the casing is peenedover the edge of the cover to hold it in place and to press it againstthe protuberances. The pressure on the protuberances comprises thebearing in the bore so that any wear on the bearing by the ball iscompensated for by the bearing being pushed towards the ball because ofits compressed state.

The joint disclosed in the aforesaid patent has the ad 7 vantage ofproperly supporting the ball and pin in the casing as the bearing wearsbut it has the disadvantage that the friction between the lower part ofthe ball and the bearing-is relative high because of the compression ofbearing material in the frusto-conical portion of the bore.-

An object of this invention is to provide a ball joint having animproved bearing. Another object of the invention is to provide abearing of the above described type adapted to be used between the balland easing of a ball and socket joint without unreasonably highfriction. Still another object of the invention is to improve upon aball joint of the type described above by reducing the friction betweenthe ball and bearing.

Other objects will become apparent from the following description withreference to the accompanying drawing in which:

FIG. 1 is a cut-away perspective view, partially in section of oneembodiment of the bearing provided by the invention; and

FIG. 2 is a side elevation, partially in section of a ball andsocketjoint provided with thebearing of FIG. I.

The foregoing objects and others are accomplished in accordance withthis invention, generally speaking, by providing a bearing of the typedescribed above and in U.S. Pat. No. 3,554,586, the disclosure of whichis incorporated herein by reference, having circumferentially spacedslots extending longitudinally from the edge of the bearing nearestthe'ball pin to a point just above the maximum cross-section of theball. Portions of the bearing are removed by these slots providingfrusto-conical segments therebetween adapted to fit within thecorresponding frustoconical portion of the bore about the ball.

More specifically, the invention provides a ball joint having a casingprovided with a bore which has a cylindrical portion through which aball pin and ball may be inserted and a cap or cover for the open end ofthe bore. That end of the bore spaced from the cover has an inwardlyextending annular flange about an aperture through which the ball pinprotrudes when the ball is positioned in the casing. A frustoconicallyshaped portion of the bore has its maximum cross-section or base mergingwith the cylindrical portion of the bore and its minimum cross-sectionadjacent the flange. A resilient bearing having an externalconfiguration corresponding substantially to that of the bore but spaceda short distance from the annular flange substantially fills the spacebetween the ball and the wall of the bore. The surface of the bearingwhich is adjacent the cover has a protuberant ring or a plurality ofspaced protuberances projecting therefrom towards the cover. When thejoint is assembled the ball with the bearing may be inserted through themouth of the bore, the cover pressed in the mouth below the surface ofthe casing and the edge of the casing peened around the edge of thecover to form an annular flange which secures the ball and bearing inthe bore of the casing. The protuberances are compressed and serve as aspring which urges the bearing against the ball and prevents spacebetween the ball and bearing from developing as the bearing wears fromrelative movement. Circumferentially spaced slots extendinglongitudinally from the edge of the bearing adjacent the frustoconicalportion of the casing permit the segments of the bearing therebetween tobe pressed substantially together about the ball without development ofexcessive pressure and friction between the ball and bearing. A groovein the wall of the bearing of less depth than the thickness of the wallmay extend fromthe closed end of the slot around the inner periphery ofthe remainder of the bearing. This groove may contain grease or similarlubricant which may extend between the walls of the slot. Preferably,the slots are spaced uniformly around the circumference of the bearingand alternate slots communicate with lubricant grooves. The bearing maybe further improved by providing a shallow annular groove in itsexternal surface between the cylindrical portion and frusto-conicalportion thereof.

The cutouts or slots in the bearing provide an effective and simplemeans for reducing the volume of bearing to be compressed between theball and the casing wall about the frusto-conically shaped portion ofthe bore when the bearing is pressed into place. The tongue-shapedsegments between the slots fold accurately around the ball as the wallsof the slots are moved towards each other to insure sealing of the ballin the bearing. Undesirable tension on the bearing and excessivefriction between the ball and bearing are avoided. This is particularlytrue if a shallow annular groove is provided between the frusto-conialportion and cylindrical portion of the outer wall of the bearing.

The slotted portion of the bearing facilitates assembly of the ball andcasing and the slots may be used alone or with the above describedgrooves for lubricant. The advantages of the invention are achievedsolely byvslight modification of the bearing which are inexpensive butgreatly improve the functioning of the ball joint.

Although it is preferred that the slots extend to a point just above themaximum diameter of the cavity in the bearing, they may be shorter butbest results are obtained if they extend through the frusto-conicalportion of the bearing. The bearing may be rubber, polyurethaneelastomer or any other suitable resilient material.

Referring now to the drawing, an embodiment of the resilient bearingprovided by the invention is illustrated generally as 8. A plurality ofcircumferentially spaced longitudinally extending slots 1 are cutthrough the bearing 8 beginning at the lower end 2 thereof and extendingupwardly to a point a short distance above the maximum diameter of thecavity for ball 9. In other words, slots I extend from that end of thebearing adapted to fit about the lower end of ball 9 and the integralball pin in the direction of axis 3 to at least the center plane of theball through which the axis 3 passes perpendicularly or slightly beyond.

A shallow groove 6 around the outer periphery of bearing 8 is providedbetween cylindrical portion 4 and frusto-conical portion 5. When bearing8 is pressed into the frusto-conical portion 11 of casing 13 with theinsertion of cover 12, the tongue-shaped segments la between slots 1 fitsnugly about ball 9. The slots 1 permit the compression of segments laabout the ball 9 without excessive compression of the resilient bearing.

Slots 1 may be used as grease chambers. In a preferred embodiment, eachslot 1 merges with a shallow lubricating groove 7 of less cross-sectionwhich extends in the direction of the axis 3 over the entire innersurface of the portion of the bearing which is not provided withslots 1. Slots 1, lubricating grooves 7 and groove 6 can be providedeasily by mass production molding techniques.

Although the invention has been described in detail for the purpose ofillustration it is to be understood that such detail is solely for thatpurpose and that variations can be made by those skilled in the artwithout departing from the spirit and scope'of the invention except asit may be limited by the claims.

I claim:

1. In a ball joint having a casing with a bore therethrough, a ball andpin, a resilient bearing between the ball and easing, a cover closingone end of the bore and an inwardly extending annular flange about theopposite open end through which the said pin protrudes, said bore havinga substantially cylindrical portion extending from the cover to belowthe maximum crosssection of the ball and a frusto-conically shapedportion merging at its maximum cross-section with the cylindricalportion and terminating adjacent the said flange, said bearing having anexternal configuration corresponding substantially to that of the boreand a cavity therein adapted to fit snugly about the ball'and an annulargroove in the external surface thereof adjacent to the juncture of thecylindrical and frusto-conical portions of the casing, said bearingbeing pressed by the cover towards the ball and having circumferentiallyspaced slots extending longitudinally therein with intermediate segmentsadjacent the. frusto-conical portion of the bore which seals the spaceabout the ball with a minimum of friction therebetween.

2. A ball joint having a casing with a bore there'- through, a ball andpin, a resilient bearing between the ball and casing, a cover closingone end of the bore, said bearing having an external surfaceconfiguration corresponding substantially to and engaging that of thebore and a cavity therein conforming to the configuration of the ball,circumferentially spaced longitudinal slots in the bearing adjacent theopposite end of the bore and intersecting an annular groove in saidexternal surface, which groove is contiguous with the surface of saidbore and which provides a channel for lubricant.

3. A ball joint of claim 2 having protuberance on the surface of thebearing adjacent the cover and compressed thereby.

4. A ball joint of claim 2 wherein the said slots are substantiallyuniformly spaced about the periphery thereof.

1. In a ball joint having a casing with a bore therethrough, a ball andpin, a resilient bearing between the ball and casing, a cover closingone end of the bore and an inwardly extending annular flange about theopposite open end through which the said pin protrudes, said bore havinga substantially cylindrical portion extending from the cover to belowthe maximum crosssection of the ball and a frusto-conically shapedportion merging at its maximum cross-section with the cylindricalportion and terminating adjacent the said flange, said bearing having anexternal configuration corresponding substantially to that of the boreand a cavity therein adapted to fit snugly about the ball and an annulargroove in the external surface thereof adjacent to the juncture of thecylindrical and frusto-conical portions of the casing, said bearingbeing pressed by the cover towards the ball and having circumferentiallyspaced slots extending longitudinally therein with intermediate segmentsadjacent the frusto-conical portion of the bore which seals the spaceabout the ball with a minimum of friction therebetween.
 2. A ball jointhaving a casing with a bore therethrough, a ball and pin, a resilientbearing between the ball and casing, a cover closing one end of thebore, said bearing having an external surface configurationcorresponding substantially to and engaging that of the bore and acavity therein conforming to the configuration of the ball,circumferentially spaced longitudinal slots in the bearing adjacent theopposite end of the bore and intersecting an annular groove in saidexternal surface, which groove is contiguous with the surface of saidbore and which provides a channel for lubricant.
 3. A ball joint ofclaim 2 having protuberance on the surface of the bearing adjacent thecover and compressed thereby.
 4. A ball joint of claim 2 wherein thesaid slots are substantially uniformly spaced about the peripherythereof.